The Food and Drug Administration (FDA) has approved ReActiv8® (Mainstay Medical), an implantable neurostimulation system, for the treatment of intractable chronic low back pain. 

Specifically, the device is approved as an aid in the management of intractable chronic low back pain associated with multifidus muscle dysfunction, as evidenced by imaging or physiological testing, in patients who have failed physical therapy and pain medications and are not candidates for spine surgery. 

According to the Company, ReActiv8 provides bilateral electrical stimulation of the L2 medial branch of the dorsal ramus nerve as it crosses the transverse process at L3. The stimulation elicits contraction of the muscle, which can lead to improvement in chronic low back pain and its disabling effects. An external programmer communicates wirelessly with the implant and can be used to customize stimulation for each user. Stimulation sessions are typically 30 minutes long and are activated twice a day via an external wireless activator.

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The approval was based on results from the ReActiv8-B clinical study, a prospective, randomized, active sham-controlled blinded trial that included 204 patients implanted with ReActiv8. The device delivered appropriate stimulation (enough to elicit episodic contractions of the multifidus muscle) to the treatment group and low stimulation (no expected effect) to the control group. The primary end point of the study was a comparison of responder rates between the treatment and control groups as measured on the visual analog scale (VAS) of pain. Responders were defined as having a ≥30% improvement between baseline and 120 days after randomization, without an increase in pain medication taken 2 weeks prior to the primary end point assessment visit.

Results showed that the responder rate at 120 days was 56% in the treatment arm vs 47% in the control arm, a difference that was not found to be statistically significant. Findings from the study also showed that among the 60 patients who crossed-over to treatment from the control group, 68% were considered responders. Additionally, among patients who took opioids at baseline, treatment with ReActiv8 was associated with a voluntary decrease in medication use. 

“ReActiv8 fills an important unmet clinical need of patients suffering from chronic low back pain,” said Chris Gilligan, MD, Chief, Division of Pain Medicine, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women’s Hospital and principal investigator of the ReActiv8-B study. “I have seen ReActiv8 provide durable improvements in back pain, the disabling effects of back pain, and quality of life.”

The Company plans to make the device available in the US in early 2021.

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This article originally appeared on MPR